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Catalyst2955 Hardware Installation Guide
78-14944-03
Chapter2 Overview
Front-Panel Description
When set for autonegotiation, a port senses the speed and duplex settings of the
attached device and advertises its own capabilities. If the attached device supports
autonegotiation, the port negotiates the best connection (that is, the fastest line
speed that both devices support and full-duplex transmission, if the attached
device supports it) and configures itself accordingly.
10/100/1000 Ports
The 10/100/1000 uplink ports on the Catalyst 2955T-12 switch use RJ-45
connectors and twisted-pair cabling. The ports can connect to these devices:
•10BASE-T devices, such as workstations and hubs, through standard RJ-45
connectors and two or four twisted-pair, Category 3, 4, or 5 cabling.
•100BASE-TX devices, such as high-speed workstations, servers, hubs,
routers, and other switches, through standard RJ-45 connectors and two or
four twisted-pair, Category 5 cabling.
•1000BASE-T devices, such as high-speed workstations, servers, hubs,
routers, and other switches, through standard RJ-45 connectors and four
twisted-pair, Category 5 cabling.
Note When connecting the switch to a 1000BASE-T device, be sure to use a four
twisted-pair, Category 5 cable.
Note When connecting the switch to workstations, servers, and routers, be sure to use
a twisted-pair straight-through cable. When connecting the switch to hubs or other
switches, use a twisted-pair crossover cable. Pinouts for the cables are described
in Appendix B, “Connectors and Cables.”
The 10/100/1000 ports on the Catalyst 2955T-12 switch can be set to operate a t
10 or 100 Mbps at half- or full-duplex mode or 1000 Mbps in f ull-duplex mode.
They can also be set for speed autonegotiation, compliant w ith IEEE 802.3ab. In
all cases, the cable length from a switch to an attached device cannot exceed
328 feet (100 meters).